The present invention relates to a machine for packaging mattresses in a sheet unwound continuously from a roll.
Mattress packaging machines are already known. A first type of these machines, shown in FIGS. 1, 2 and 3, comprises a frame provided with a horizontal surface 1 for supporting the mattress 2, at the end of which there is a tensioning roller 3 for guiding, at right angles to the surface 1, a packaging sheet 4 (usually made of plastics) unwound from a roll 4a. As the mattress 2 advances in the direction F, from the supporting surface 1 onto the package receiving surface 5, the sheet 4 (as shown in FIG. 2) is folded and stretched over and under the mattress 2, so as to form a bag which is then closed at the rear (see FIG. 3) and on both sides by heat-sealing.
Packaging defects often occur in these conventional packaging machines being due to the fact that the sheet unwound from the roll slides on the front edge of the mattress and therefore tends to form unsightly longitudinal creases and wrinkles owing to the unevenness and flexible consistency of the front edge.
In order to avoid these drawbacks, it has been proposed (FIGS. 4, 5 and 6) to push the mattress 2 against the sheet 4 by using a pusher 6 having an arm 7 which lies above the mattress, reaches beyond the front edge of said mattress and supports a roller 8 being parallel to the front edge of the mattress.
The roller 8 acts as a redirection element for the packaging sheet 4, preventing its contact with the front edge of the mattress and thus preventing the formation of creases.
The refinement of the roller supporting arm 7 in these packaging machines, however, entails a longer production cycle, since the arm 7 has to be fully returned above the supporting surface in order to clear the receiving surface for the descent of the heat-sealing bars that have to provide the heat-seal that closes the bag perimetrically.
The aim of the present invention is to provide a packaging machine which allows to avoid the formation of creases of the package without compromising the operating times.
This aim is achieved with a packaging machine whose characteristics are defined in the appended claims.